Known in the art is a compression ignition type internal combustion engine which arranges a particulate filter for trapping particulate matter in exhaust gas at the inside of an exhaust passage. As a result, the quantity of particulate matter which is discharged into the atmosphere is suppressed.
In this regard, if the quantity of particulate matter on the particulate filter becomes greater, the pressure loss of the particulate filter will gradually become greater. As a result, the engine output is liable to drop.
Therefore, known in the art is an internal combustion engine which performs PM removal control which maintains the particulate filter in an oxidizing atmosphere while making the particulate filter rise in temperature and thereby makes the particulate matter burn off from the particulate filter (see PLT 1). In this internal combustion engine, the pressure difference between the upstream and downstream sides of the particulate filter is detected and the PM removal control is performed when the pressure difference becomes a predetermined upper limit value or more.